The world's longest flight is once again available to American tourists

If you're looking for an aviation-focused adventure, Singapore Airlines might have a good option for you.

The airline operates the world's longest flight, from New York-JFK to Singapore. But throughout the pandemic that 9,537-mile, 19-hour route has largely been off-limits to most travelers.

Now, thanks to the recent news about Singapore relaxing entry requirements for vaccinated Americans, the flight is once again within reach for many.

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Beginning on Oct. 19, Singapore will expand its vaccinated travel lanes entry policy, which allows for quarantine-free travel between Singapore and select countries. The next tranche of countries to be added to the program include the U.S., Canada and European nations, like Denmark, France, Italy, the Netherlands, Spain and the U.K.

Travel from Singapore to these countries can be on any Singapore Airlines flight, while travel from these countries to Singapore must be on designated Vaccinated Travel Lane (VTL) flights.

The airline has unveiled an initial list of flights that qualify for quarantine-free travel to Singapore, and the world's longest one is on the list. Singapore Flight 23 departs New York-JFK at 10:30 p.m. and arrives two days later at 5:20 a.m. The return, Singapore Flight 24, departs Singapore at 1:15 a.m. and arrives at 7:55 a.m. on the same day, all times local.

I flew the world's longest flight before the pandemic when it was operating from Newark. (The airline has since moved the service to JFK, adding three miles to the overall route.) Sitting in business class for over 17 hours was a real treat, and I arrived as refreshed as one possibly could after sitting in a metal tube for so long.

Singapore's legendary service and food and beverage program made the time fly by, though I was definitely ready to get off the plane by the end of the journey. The flight is again operated by the airline's Airbus A350-900ULR (ultra-long-range), featuring 67 business-class pods and 94 premium economy recliners.

Round-trip fares currently start at around $1,400 for premium economy or $4,000 for business class. You can book awards through Singapore's KrisFlyer loyalty program starting at 73,000 miles for premium economy, or 99,000 miles in biz. There's plenty of availability in premium economy, though biz availability is sporadic at best.

Historically, redeeming Alaska Airlines Mileage Plan miles has been a popular option for scoring awards in Singapore's long-haul biz, though Singapore is only now in the process of releasing partner award availability after a 14-month hiatus. Mileage Plan didn't show any availability for the world's longest flight at press time.

In addition to the world's longest flight, Singapore Airlines is also resuming service to Canada after a nearly 12-year hiatus. The airline announced on Monday that it'll add a triangle route from Singapore to Vancouver and onwards to Seattle for the busy winter holiday period between Dec. 3, 2021, and Feb. 15, 2022. This service will replace existing Singapore to Seattle nonstops previously operated by the airline.

Clearly, the carrier is hoping to capture as much demand as it can for the new travel scheme.

Though it's exciting that Singapore is reopening to Americans, there remains one big caveat that could make or break your travel plans: only certain types of vaccine cards can be used as proof of vaccination.

According to the airline, "only the Smart Health Card (SHC) format, issued by Canada or the USA on the Common Trust Network are accepted." A handful of states, including California and New York, as well as some nationwide pharmacies like CVS and Walmart, use this digital format. You can find the full list here.

If you've been vaccinated elsewhere, you'll need to wait until the country relaxes its rules to embark on this aviation-focused adventure.